Feline neuronal GM1 gangliosidosis, an inherited disease recently discovered in Siamese cats by this laboratory, appears to be a nearly exact replica of juvenile GM1 gangliosidosis of children and, therefore, has exceptional value as an experimental model of the gangliosidoses and CNS lysosomal diseases of man. Continuation of preliminary studies will make possible the preservation and expansion of the existing mutant cat stock for basic and applied research in this and other laboratories. Specific research objectives include: (a) full characterization of the feline disease in biochemical, morphological, genetic and clinical terms, (b) establishment and utilization of a fibroblast culture system for in vitro studies of basic disease processes and testing of theoretical therapeutic measures, (c) evaluation of a variety of promising in vivo therapeutic measures including organ transplantation, (d) search for additional animal models of inherited CNS diseases & (e) physiochemical characterization of normal and mutant feline GM1 ganglioside beta- galactosidases.